Grant funds are requested to support a new research Program Project aimed at initiating an exploration of the potential of embryonic stem (ES) cell transplantation for restoring lost functions after spinal cord injury. Members of the proposed Project team have already developed experience working with mouse ES cells differentiated down neural lineages, methods for reducing cell death in the nervous system, and rodent models of traumatic spinal cord injury. In the experiments that form the specific background for the present proposal, Project team members have obtained evidence that mouse ES-cell derived neural lineage cells (ESNLCs) can be successfully transplanted into the syrinx/cyst that forms nine days after impact injury to the rat spinal cord . These transplanted ESNLCs survived for at least many weeks, partially filling the syrinx and migrating into host tissue, and expressed markers for differentiated oligodendrocytes, astrocytes, and neurons. The requested Program Project funding would enable Project team members to build on these early experiments in a systematic and hypothesis-driven fashion. Based on direct observations that a majority of transplanted ESNLCs die over the first 48 hours following transplantation and that neurons in particular continue to die over subsequent days, the emphasis of the experiments proposed here will be on improving the survival of transplanted ESNLCs through pharmacological and genetic engineering approaches aimed at blocking apoptosis and excitotoxicity. It is anticipated that work performed in subsequent years may be directed at optimizing the ESNLC transplantation procedure in other ways.